Landslide susceptibility mapping in the western Słonne Góry (SE Poland): a comparative study of landslide polygons and buffer zones using the Frequency Ratio Method

Abstract

A high variability of landslide density and distribution was observed in the western part of the Słonne Góry (Sanok region, Eastern Carpathians, SE Poland). A statistical method, the bivariate Frequency Ratio Model (FRM), was used to show the reasons for this variability and to compile a map of landslide susceptibility for the study area. The landslide susceptibility map was calculated using an inventory of previous landslides and using buffer zones mapped around the upper parts of landslides. The polygons of landslides represented disturbed features and slope properties. In contrast, buffer zones represented undisturbed slope features and properties. Both methods gave similar results. Two landslide susceptibility maps were obtained with the following Area Under the Curve (AUC) values: 0.7936 for landslides and 0.7971 for buffer zones. This indicates a sufficiently good fit of the computational models for predicting new landslides. Unfortunately, the use of buffer zones in the calculations, which represent undisturbed slope properties, did not improve the predictive values of the susceptibility maps. Significant differences were shown as regards slope angle. The importance of this parameter (slope angle) for the Polish part of the Carpathians was better enhanced by the use of buffer zones in the landslide susceptibility calculations